1. Field of the Invention
This invention relates to an air intake system for supplying air to an engine of a forklift, and a forklift equipped with the air intake system. The air intake system is useful when applied in realizing a forklift in which the air intake system is in a compact configuration, and intake noise is markedly reduced.
2. Description of the Related Art
In an engine-powered forklift, whose vehicle runs by using an engine as a power source, such as a diesel engine or a gasoline engine, and which does cargo handling work by a hydraulic device, the engine is installed at the center of the vehicle. An air intake system for supplying air to the engine is disposed in a side portion of the vehicle.
FIG. 11 is an exploded perspective view showing an example of the configuration of a conventional air intake system (non-patent document 1; Toyota Forklift Parts Catalog 1999.01 Catalog No. 5G121-991, TOYOTA MOTOR CORP./TOYODA AUTOMATIC LOOM WORKS, LTD.). In an air intake system 1 of a forklift illustrated in this drawing, air is taken in through an air intake port 3 provided in an upper portion of a rear pillar 2, and flows downward through a passageway within the rear pillar 2. Then, the air flows through a hose-shaped duct 4, an expansion silencer 5, a hose-shaped duct 6, and an air cleaner 7 in this sequence. After purification by the air cleaner 7, the air is supplied to a combustion chamber of an engine (not shown) via a hose-shaped duct 8. Intake noise generated at this time is reduced by the expansion silencer 5.
FIG. 12 is an exploded perspective view showing another example of the configuration of a conventional air intake system (non-patent document 2; PARTS CATALOG NISSAN FORKLIFT MODEL D02 (S) SERIES MAY 2000 ISSUE Pub. No. CF-420-S). In an air intake system 11 of a forklift, illustrated in this drawing, air is taken in through an air intake port (not shown) provided in an upper portion of a rear pillar 12, and flows downward through a passageway within the rear pillar 12. Then, the air flows through a hose-shaped duct 13 and an air cleaner 14 in this sequence. After purification by the air cleaner 14, the air is supplied to a combustion chamber of an engine (not shown) via a hose-shaped duct 15. A resonance silencer 16 is also connected to the rear pillar 12.
With a forklift, it is desired to minimize the noise level at the ears of an operator who operates the forklift. The European CEN standards, for example, obligate vehicles to have a label attached thereto which explicitly describes the noise level (dB) at the ears of the operator. Intake noise generated by the air intake system contributes greatly to the above noise level.
Thus, it is important to decrease the intake noise. Upsizing a silencer or increasing the number or types of silencers for this purpose, however, results in upsizing of the air intake system if it has the configuration of the above-mentioned conventional air intake system 1 or 11.
In detail, the air intake system of FIG. 11 is configured to use the hose-shaped ducts 4 and 6, and does not effectively use the space below the air cleaner 7, thus making it difficult to achieve a compact configuration. Moreover, the air intake system has many seams, etc. The air intake system of FIG. 12 is also configured to use the hose-shaped duct 13, and does not allow effective use of the space below the air cleaner 14, thus posing difficulty in achieving a compact configuration.